Almost exactly 25 years ago, when there was no YouTube and Sammy Yatim wasn’t even a gleam in his parents’ imagination, Lester Donaldson was shot and killed by Metro Police, as the force was then called, in the west-end Toronto rooming house where he lived.

It was the shooting of the 44-year-old, a diagnosed paranoid schizophrenic with a history of violence, and that of a 17-year-old named Wade Lawson in nearby Peel Region, an unarmed black teenager who died at the wheel of a stolen car about four months later, which indirectly led to the formation of the Special Investigations Unit.

It is the independent agency that probes serious incidents involving Ontario police officers, and which is now investigating Sammy’s shooting death early Saturday morning.

First, former judge Clare Lewis was appointed to head a task force on race relations and policing. He then recommended that the formation of an outside force, and in 1990, the SIU was born.

If it all feels like déjà vu all over again — as Yogi Berra famously put it — well, that’s only because in some real ways it is.

Back then, it was the late black activist Dudley Laws and the lawyer Charlie Roach, who died just last year, who often led the angry marches, during which police were routinely called murderers.

A few days after Donaldson’s death on Aug. 9, 1988, The Globe and Mail reported that 600 angry people marched to 13 Division, where the officer who shot him, then-Constable David Deviney, worked.

The hot issues in those days were the troubled relations between black Torontonians and the police; the fact that at the time police investigated themselves (as one well-known activist, Bromley Armstrong, put it rather brilliantly, “If I should beat my wife, you don’t ask my cousins to investigate”), and the lack of training for police in dealing with the mentally ill.

Ultimately, Deviney was charged with manslaughter in Donaldson’s death, two Peel Region constables charged with second-degree murder in Lawson’s.

All were acquitted later by juries, though for Deviney, things didn’t end there, because what followed was what became the longest-running coroner’s inquest in Canadian history.

Early Monday evening, a crowd not much bigger than the one that all those years ago gathered in Lester Donaldson’s name, gathered in Sammy Yatim’s.

They marched to 14 Division, the police station of the as-yet unidentified officer who fired nine times at the 505 Dundas West streetcar, killing the 18-year-old.

Civilian-shot video of the shooting was in the modern fashion smartly uploaded to YouTube shortly afterwards and has been viewed around the world.

It gets no easier to watch, however many times you may try.

These protesters carried placards, just as their predecessors did a quarter-century ago, chanted “Shame! Shame!”, and hurled invective in the faces of officers on bicycles who had the misfortune of being assigned to manage the march.

My suspicion is many of those officers may be mortified all by their lonesome, thanks very much, and need no helpful prodding to feel badly.

Among themselves, cops have a shorthand for such terrible incidents: What they ask each other is, was the shooting a “good” one or not?

Of course it doesn’t mean a shooting is actually ever good, or approved.

But there are shootings which are “good,” that is which are “justified,” where an officer clearly had reason to resort to lethal force and where his colleagues immediately understand why he would have done so.

At first blush, and maybe beyond that, this one doesn’t smell like one of those.

There are a couple of powerful indicators.

The first is that Toronto Police Chief Bill Blair, though he is precluded by law (the SIU is the investigative agency here and makes the public statements) from saying anything other than what he said Monday, nonetheless offered his condolences to Sammy’s family and said he shares the public’s concern.

A second indicator is that the officer who fired at Sammy already has been suspended, something that is certainly within the power of a police chief, but is neither usual nor routine.

What is unhelpful is misinformation, such as city councillor Janet Davis tweeting that Sammy was “cornered on an empty streetcar” and asking “where was the Mobile Crisis Intervention Team?”, the teams of cops and mental-health workers who Davis said were “put in place across the city for incidents just like this”. Councilor Adam Vaughan said something similar on Newstalk 1010 Monday morning.

The crisis teams, in fact, are expressly not to attend calls where people are intoxicated, or violent, or have weapons. They are generally off-shift before midnight.

There has been progress since Lester Donaldson died.

The SIU, while imperfect and allegedly without the resources it needs, nonetheless is in its 23rd year of operation. Cops haven’t investigated cops for a long time in this province.

Back then, critics were arguing that police should have pepper spray; now they do, and in Ontario, sergeants and senior officers carry Tasers.

There are police mental health teams in 12 Toronto divisions, and if there should be more of them, or if their mandate or hours should be expanded, they exist.

And dealing with troubled people — and at least on the night he died, Sammy Yatim was troubled, having exposed himself at one point, ordered people off the streetcar and armed himself with a knife — will always be the hardest and least predictable part of the police officer’s job.

It’s a bloody shame, all of it — for the young man and those who loved him, for the good men and women of the force, and for the officer now at the centre of what will surely be a long and terrible firestorm.